Thursday, January 8, 2009

Counting ATPs

Students usually ask me how to count the number of ATPs formed during cell respiration. So I have prepared the following table that summarizes how and where ATPs are formed.

Before we go to that however, I just wish to point out that there are two ways by which ATP is formed. One is through substrate level phosphorylation and the other is through oxidative phosphorylation. During substrate level phosphorylation, 1 molecule of ATP is formed during each process. During oxidative phosphorylation however, 2 or 3 molecules of ATP are formed per process depending on the first hydrogen acceptor. If FAD is the first hydrogen acceptor, then 2 ATPs are formed while 3 ATPs are formed if NAD is the first hydrogen acceptor.

Another thing, we have to multiply by 2 all the ATPs formed because there are 2 molecules of pyruvic acid formed after glycolysis.

* 4ATPs are actually formed. However, 2ATPs are used to prime glucose for the process.

**one step during glycolysis converts glyceraldehyde3phosphate(G3P) to 1,3diphosphoglycerate(1,3DPGA). This releases hydrogen ions and electrons that are accepted by NAD and brought to the mitochondrion through a glycero-phosphate shuttle (GP). So only 2 ATPs (instead of 3) are formed here (even if NAD is the acceptor) because 1 ATP is used to "pay" the GP shuttle.

Welcome

Hi,Welcome to my cell blog. The reason for this blog is written in my first post "why this blog" last October. Writing/talking about cells has developed into a kind of mission for me. I hope you will join me daily or visit every now and then and discover or rediscover more about the wonders of the cell.

This blog is dedicated to my former students and teachers who inspired me through the years. It is especially dedicated to the high school teachers who requested me to write a book. This might serve as a prelude to a book, who knows.

Please leave comments if anything strikes you or you may write me at my email - baby.angtuaco@gmail.comIf you have questions or if you want me to write anything about cells please tell me too. We can work on this together.

I got several blogs one of which is: http://getinspired-photoquotes.blogspot.com/ wherein I share inspirational quotes with photos. I also have other blogs on photography, happiness, and science, as well as about the Philippines.